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X-rays from colliding stellar winds: the case of close Wolf-Rayet+O binary systems
Zhekov, Svetozar A.
We have analysed the X-ray emission from a sample of close Wolf-Rayet+O (WR+O) binaries using data from the public Chandra and XMM-Newton archives. Global spectral fits show that two-temperature plasma is needed to match the X-ray emission from these objects, because the hot component (kT > 2 keV) is an important ingredient of the spectral mode…
Characterizing the Atmospheres of Transiting Planets with a Dedicated Space Telescope
Ollivier, M.; Ribas, I.; Encrenaz, T. +12 more
Exoplanetary science is one of the fastest evolving fields of today's astronomical research, continuously yielding unexpected and surprising results. Ground-based planet-hunting surveys, together with dedicated space missions such as Kepler and CoRoT, are delivering an ever-increasing number of exoplanets, over 690, and ESA's Gaia mission will esc…
Globular cluster systems as tracers of environmental effects on Virgo early-type dwarfs
Aguerri, J. A. L.; Sánchez-Janssen, R.
Early-type dwarfs (dEs) are by far the most abundant galaxy population in nearby clusters. Whether these objects are primordial, or the recent end products of the different physical mechanisms that can transform galaxies once they enter these high-density environments, is still a matter of debate. Here we present a novel approach to test these sce…
Density variations within the south polar layered deposits of Mars
Zuber, Maria T.; Plaut, Jeffrey J.; Phillips, Roger J. +3 more
The south polar layered deposits (SPLD) constitute the largest known reservoir of water on Mars. Previous studies solved for the best fit uniform density of the deposits using a forward approach. Here we invert for the lateral density variations in the layered deposit using gravity data from radio tracking of Mars Reconnaissance Orbiter, topograph…
Transiting exoplanets from the CoRoT space mission. XXI. CoRoT-19b: a low density planet orbiting an old inactive F9V-star
Mazeh, T.; Aigrain, S.; Alonso, R. +51 more
Context. Observations of transiting extrasolar planets are of key importance to our understanding of planets because their mass, radius, and mass density can be determined. These measurements indicate that planets of similar mass can have very different radii. For low-density planets, it is generally assumed that they are inflated owing to their p…
X-ray pulsations from the region of the supergiant fast X-ray transient IGR J17544-2619
Hill, A. B.; Bird, A. J.; McBride, V. A. +5 more
Phase-targeted RXTE observations have allowed us to detect a transient 71.49 ± 0.02 s signal that is most likely to be originating from the supergiant fast X-ray transient IGR J17544-2619. The phase-folded light curve shows a possible double-peaked structure with a pulsed flux of ~4.8 × 10-12 erg cm-2 s-1 (3-10 keV…
Principal component analysis of background and sunspot magnetic field variations during solar cycles 21-23
Zharkova, V. V.; Shepherd, S. J.; Zharkov, S. I.
The aim of this paper is to derive the principal components (PCs) in variations of (i) the solar background magnetic field (SBMF), measured by the Wilcox Solar Observatory with low spatial resolution for solar cycles 21-23, and (ii) the sunspot magnetic field (SMF) in cycle 23, obtained by SOHO/MDI. For reduction of the component dimensions, princ…
The Faint-end Slope of the Redshift 5.7 Lyα Luminosity Function
Martin, Crystal L.; Sawicki, Marcin; Dressler, Alan +2 more
Using new Keck DEIMOS spectroscopy, we examine the origin of the steep number counts of ultra-faint emission-line galaxies recently reported by Dressler et al. We confirm six Lyα emitters (LAEs), three of which have significant asymmetric line profiles with prominent wings extending 300-400 km s-1 redward of the peak emission. With thes…
The role of electrons during chorus intensification: Energy source and energy loss
Zong, Q. -G.; Cao, J. B.; Huang, S. Y. +4 more
The role of electrons during the shock-induced chorus intensification observed by THEMIS D on 19 November 2007 is investigated in detail. First, the electrons are accelerated through the local betatron acceleration and radial diffusion, which are primarily in the perpendicular direction and result in the positive anisotropy (T⊥>T
Two short mass-loss events that unveil the binary heart of Minkowski's Butterfly Nebula
Bachiller, R.; Chesneau, O.; Bujarrabal, V. +3 more
Context. Studying the appearance and properties of bipolar winds is critical to understand the stellar evolution from the AGB to the planetary nebula (PN) phase. Many uncertainties exist regarding the presence and role of binary stellar systems, mainly due to the deficit of conclusive observational evidences.
Aims: We investigate the extended…